1. Field of the Invention
The present invention relates to the recording and the reproducing of data onto and from a floppy disk (FD), and more particularly to a head controlling device provided in a disk apparatus to precisely move a head stepwise to the position of each track on a recording surface of a disk.
2. Description of the Related Art
In conventional floppy disk drive apparatuses, a stepwise driving mechanism using, for example, a stepping motor is used as a head-advancing device for moving a head stepwise to the position of each track on a recording surface of a disk. Data is concentrically recorded on the tracks of the disk. The head is positioned at the position of each track as a result of a mechanical stepwise operation of the head-advancing device.
In some disk apparatuses, a head-advancing device of the linear driving type which can move the head continuously is provided. In such disk apparatuses, a detecting section detects the position of the head that is moved by the head-advancing device. Based on the outputs from the detecting section, determinations are made as to whether or not the head has arrived at the positions of each of the tracks on a recording surface of a disk.
In some disk apparatuses including a head-advancing device of the linear driving type, a high-density-recording disk (on which servo signals used for tracking operations are recorded) and a floppy disk (FD) can both be loaded. When the high-density-recording disk is loaded into the disk apparatus, the head is moved by linear driving. When the head reads the servo signals, determinations are made that the head has been positioned at each of the tracks. On the other hand, when the floppy disk is loaded into the disk apparatus, the head-advancing position is controlled on the basis of detection outputs from the detecting section to position the head at the position of each track.
FIG. 3 illustrates an example of detection outputs from the detecting section when the head has been advanced. In FIG. 3, position R to which the head is moved in a radial direction of the disk is indicated along the horizontal axis, whereas detection output voltage V (or time) is indicated along the vertical axis. A phase A detection output and a phase B detection output are out of phase by xcfx80/2 (rad). When, for convenience, values halfway between the amplitude peaks (P-P) of the detection outputs are defined as the zero points, the phase A detection output is a sine curve and the phase B detection output is a cosine curve, or these detection outputs are curves that approximate to those based on these trigonometric functions.
Conventionally, a standard (or alignment) disk is loaded onto a rotational drive section of a disk apparatus and is rotated. While the head is moving in a radial direction of the disk, reproduction outputs from the head are inspected. When the reproduction outputs reach the peak values, and the head is positioned at the position of a track on the standard disk, the mounting position of the detecting section is adjusted so that either the phase A detection output or the phase B detection output becomes 0.
When a floppy disk is loaded into a disk apparatus adjusted in the above-described manner in order to carry out a recording or a reproducing operation, a controlling section monitors the detection outputs from the detecting section. When the phase A detection output and the phase B detection outputs become 0, the advancement of the head is stopped, so that the head is moved stepwise and positioned at the position of each of the tracks.
However, in the above-described conventional method of controlling the advancement of the head, many manhours are needed to adjust the mounting position of the detecting section because it needs to be carried out while observing the detection outputs illustrated in FIG. 3. In addition, skill and experience are required to adjust the mounting position of the detecting section. Further, it is difficult to adjust the phase A and the phase B detection outputs exactly at zero when the head has reached the position of a track, so that adjustment errors inevitably occur.
Accordingly, in order to overcome the above-described problems, it is an object of the present invention to provide a head-controlling device of a disk apparatus in order to allowing precise positioning of a head in correspondence with the position of each track, without having to adjust the position of a detecting section that provides phase A and phase B detection outputs, and without having to carry out precise adjustments.
To this end, according to one aspect of the present invention, there is provided a head-controlling device of a disk apparatus, the disk apparatus comprising a rotational drive section for rotating a disk; a head opposing a recording surface of the disk; head-advancing means for advancing the head in a radial direction of the disk; a detecting section whose detection outputs change in accordance with a movement of the head; and a controlling section for controlling the head-advancing means based on the detection outputs obtained from the detecting section in order to move the head stepwise to the position of a track on the recording surface of the disk;
wherein the detecting section outputs either trigonometric function values of phases A and B that are out of phase or values of curves that approximate to those based on the trigonometric functions of the phases A and B that are out of phase; and
wherein the controlling section retains the phase A and the phase B values produced when the head reaches the track, and, during a recording or a reproducing operation on the disk, controls the head-advancing means so as to stop the head when the phase A value or the phase B value detected from the detecting section matches the phase A value or the phase B value retained in the controlling section.
Although not exclusive, in one form of one aspect of the present invention, the phase A and the phase B values retained by the controlling section may be values other than trigonometric function values or values of halfway between amplitude peaks of the trigonometric-function-value-based curves.
According to the present invention, the detecting section is an optical means, a magnetic means, or the like. It is preferable that the phase A and the phase B detection outputs are out of phase by xcfx80/2 (rad). Here, the two phase detection outputs are based on sine and cosine functions, respectively, or functions-approximate to these functions.
According to the present invention, in the case where a recording or a reproducing operation is performed on the disk that is loaded, a determination is made that the head has reached the position of the track not based on the position when the phase A and the phase B detection outputs become 0, but based on when the phase A detection output or the phase B detection output becomes a predetermined value. Therefore, it is possible to determine that the head has reached the position of the track when a recording or a reproducing operation is performed on a disk, without having to adjust the mounting position of the detecting section during the manufacturing process. Therefore, it is possible to control the stepwise movement of the head with high precision.
Although not exclusive, in another form of one aspect of the present invention, the controlling section may retain the phase A and the phase B values produced when the head reaches the position of the track, with the values being obtained using highly linear areas of the areas of the phase A and the phase B detection outputs, obtained from the detecting section, located within an amplitude range that is smaller than a peak-to-peak amplitude range, the highly linear areas of the phases A and B being mutually continuous in terms of time.
Accordingly, when areas of the phase A and the phase B detection outputs having a high degree of linearity are only used, the stepwise movement of the head can be controlled with high precision.
According to a second aspect of the present invention, there is provided a head-controlling device of a disk apparatus, the disk apparatus comprising a rotational drive section for rotating a disk; a head opposing a recording surface of the disk: head-advancing means for advancing the head in a radial direction of the disk; a detecting section whose detection outputs change in accordance with a movement of the head; and a controlling section for controlling the head-advancing means based on the detection outputs obtained from the detecting section in order to move the head stepwise to the position of a track on the recording surface of the disk;
wherein in accordance with a movement of the head the detecting section outputs either trigonometric function values or values of curves approximate to those based on the trigonometric function values of phases A and B that are out of phase; and
wherein the controlling section retains a value showing a relationship between the values of the phases A and B produced when the head reaches the position of the track, and, during a recording or a reproducing operation on the disk, calculates the phase A value and the phase B value detected from the detecting section in order to control the head-advancing means so as to stop the head when the calculated result matches the relational value.
Accordingly, when the relational value showing a relationship between the phase A and the phase B value is determined, and the head-advancing position is controlled based on this relational value, it is possible to smoothly control the alignment of the head with the track position even when the phase A and the phase B detection outputs are out of phase by a specified value such as xcfx80/2 (rad) due to manufacturing errors in the detecting section.
Although not exclusive, in one form of the second aspect of the present invention, the relational value may be the sum of or the difference between the phase A and the phase B values produced when the head reaches the position of the track.
Although not exclusive, in another form of the second aspect of the present invention, when the phase A and the phase B detection outputs plotted on an X-Y coordinate system, with X and Y axes intersecting at right angles, and when the phase A and the phase B values are An and Bn when the head is aligned with the track, an inclination angle xcex8 made by a line connecting the center of the coordinate system and a point of intersection of lines drawn from X=An and Y=Bn, on the coordinate system, may be equal to the relational value.
Although not exclusive, xcex8 may be easily calculated from Formula 1 in which x is an arbitrary value.
When this calculation is performed, xcex8 is the only variable used in controlling the head position, thereby facilitating the detection of the head position.
Although not exclusive, in a form of the first aspect or the second aspect of the present invention, when a standard disk is placed on the rotational drive section, and the head reaches the position of a track on the standard disk, the phase A and the phase B values obtained from the detecting section or the relational value may be retained in a retaining section.